Exhaust system mounting structure for vehicle

ABSTRACT

An exhaust port formed on one side portion of an engine body along the vehicle width direction, the exhaust port connected to an exhaust muffler arranged in an extending manner in the vehicle width direction along a rear edge of the vehicle body frame by way of an exhaust pipe passage means that introduces an exhaust gas from the exhaust port. The exhaust pipe passage means is arranged in an extending manner in the longitudinal direction of the vehicle while having a bent portion bent toward the center in the vehicle width direction from one side of the engine body in the vehicle width direction behind the engine body, as viewed in a plan view.

BACKGROUND

1. Field

Embodiments of the present invention relate to a vehicle where an enginebody of an internal combustion engine and a transmission which iscontiguously mounted on the engine body so as to constitute a power unitcooperatively with the internal combustion engine, are mounted on anintermediate portion of a vehicle body frame in the longitudinaldirection of the vehicle. Embodiments of the present invention moreparticularly relate to the improvement of the exhaust system mountingstructure.

2. Description of the Related Art

When an engine body and a transmission are arranged on an intermediateportion of a vehicle in the longitudinal direction of the vehicle, it isdifficult to ensure a space for routing an exhaust pipe. In view of theabove, in the technique disclosed in, for example, U.S. Laid-Open PatentPublication 2004/0195019 (Patent Literature 1), the exhaust pipe isarranged in a vertically meandering manner between the engine body andan exhaust muffler arranged behind the engine body.

SUMMARY

However, in the technique disclosed in Patent Literature 1 where theexhaust pipe vertically meanders, although a pipe length of the exhaustpipe can be ensured, the exhaust pipe becomes complicated so that thenumber of bending portions of a pipe passage is increased leading alsoto the increase of the pipe passage resistance.

The present invention has been made in view of the above-mentionedcircumstances, and it is an object of the present invention to providethe exhaust system mounting structure for a vehicle where a pipe passagefrom an exhaust port to an exhaust muffler is arranged such that a pipepassage length can be ensured while decreasing the number of bendingportions in a state where a volume of the exhaust muffler is ensured.

To achieve the above-mentioned object, according to certain embodiments,in a vehicle where an engine body of an internal combustion engine and atransmission which is contiguously mounted on the engine body so as toconstitute a power unit cooperatively with the internal combustionengine are mounted on an intermediate portion of a vehicle body frame inthe longitudinal direction of the vehicle, an exhaust port is formed onone side portion of the engine body in the vehicle width direction. Theexhaust port is connected to an exhaust muffler arranged in an extendingmanner in the vehicle width direction along a rear edge of the vehiclebody frame by way of an exhaust pipe passage means which introduces anexhaust gas from the exhaust port. The exhaust pipe passage means isarranged in an extending manner in the longitudinal direction of thevehicle while having a bent portion which is bent toward the center inthe vehicle width direction from one side of the engine body in thevehicle width direction behind the engine body as viewed in a plan view.

In other embodiments, the exhaust pipe passage means includes a catalystconverter which extends in the longitudinal direction of the vehiclebetween a pair of left and right suspensions which supports a pair ofleft and right rear wheels on the vehicle body frame in a suspendingmanner.

In other embodiments, a joint that separably connects a portion of theexhaust pipe passage means on an engine body side and a portion of theexhaust pipe passage means on an exhaust muffler side to each other isinterposed in the bent portion of the exhaust pipe passage means, and afastening member of the joint is arranged in an extending manner in thevertical direction in a frontwardly and downwardly inclined manner so asto enable the manipulation of the fastening member from below thevehicle body frame.

In other embodiments, exhaust-muffler-side hooks that extend toward afront side are fixedly mounted on a plurality of dispersed portions ofthe exhaust muffler. A plurality of vehicle-body-frame-side hooksindividually corresponding to the exhaust-muffler-side hooks are fixedlymounted on the vehicle body frame in an extending manner toward a rearside. The exhaust-muffler-side hooks and the vehicle-body-frame-sidehooks corresponding to each other are connected to each other by way ofelastic members enabling the hooks to be inserted into the elasticmembers and to engage with the elastic members.

In other embodiments, a rear floor positioned above the exhaust muffler,which is covered with a guard member from behind, is supported on a rearportion of the vehicle body frame, and a trailer hitch arranged belowthe exhaust muffler is fixed to a rear end of the vehicle body frame.

According to certain embodiments, the exhaust pipe passage meansconnecting the exhaust port of the engine body and the exhaust mufflerextends in the longitudinal direction of the vehicle while having a bentportion which is bent toward the center in the vehicle width directionfrom one side of the engine body in the vehicle width direction behindthe engine body, as viewed in a plan view. Accordingly, it is possibleto ensure the engine performance by ensuring a pipe passage length fromthe exhaust port to the exhaust muffler while decreasing bending of theexhaust pipe passage means. Further, the exhaust muffler is arranged inan extending manner in the vehicle width direction along the rear edgeof the vehicle body frame and hence, an excellent noise preventioneffect can be obtained by ensuring a volume of the exhaust muffler.

According to certain embodiments, the exhaust pipe passage meansincludes the catalyst converter. Accordingly, compared to the structurewhere a catalyst is stored in the inside of the exhaust muffler, it ispossible to acquire an excellent noise prevention effect by sufficientlyensuring a volume of the exhaust muffler. Further, the catalystconverter extends in the longitudinal direction of the vehicle betweenthe pair of left and right suspensions that support the pair of left andright rear wheels on the vehicle body frame in a suspending manner andhence, a heat generating portion attributed to a catalyst can bepositioned away from the outside by covering the heat generating portionwith the left and right suspensions and the rear exhaust muffler.

According to certain embodiments, the joint that separably connects aportion of the exhaust pipe passage means on the engine body side and aportion of the exhaust pipe passage means on the exhaust muffler side isinterposed at the bent portion of the exhaust pipe passage means, andthe fastening member of the joint is arranged in an extending manner inthe vertical direction while being inclined frontwardly and downwardlyin a state where the fastening member can be manipulated from below thevehicle body frame. Accordingly, a pipe passage length of the exhaustpipe passage means can be ensured and, at the same time, fastening andseparating operations of the joint can be performed from below thevehicle body frame thus enhancing maintainability.

According to other embodiments, a plurality of exhaust-muffler-sidehooks fixedly mounted on the exhaust muffler and extend toward a frontside and a plurality of vehicle-body-frame-side hooks fixedly mounted onthe vehicle body frame and extend toward a rear side, are connected toeach other by way of the elastic members that enable the hooks to beinserted into the elastic members and to engage with the elasticmembers. Accordingly, the exhaust muffler can be easily assembled to thevehicle body frame from behind the vehicle body frame and hence,assembling property can be enhanced.

According to other embodiments, the rear floor which is supported on therear portion of the vehicle body frame is arranged above the exhaustmuffler covered with the guard member from behind, and the trailer hitchfixed to the rear end of the vehicle body frame is arranged below theexhaust muffler. Accordingly, it is possible to miniaturize the guardmember dedicated to covering the exhaust muffler by protecting theexhaust muffler by the rear floor and the trailer hitch from above andbelow.

BRIEF DESCRIPTION OF THE DRAWINGS:

FIG. 1 is a longitudinal cross-sectional side view of an off-roadtraveling four-wheeled vehicle, and a cross-sectional view taken along aline 1-1 in FIG. 2.

FIG. 2 is a view as viewed in the direction indicated by an arrow 2 inFIG. 1.

FIG. 3 is a cross-sectional view taken along a line 3-3 in FIG. 1.

FIG. 4 is an enlarged view of an essential part of the off-roadtravelling four-wheeled vehicle shown in FIG. 1.

FIG. 5 is a view as viewed in the direction indicated by an arrow 5 inFIG. 4.

FIG. 6 is a plan view showing the arrangement of an exhaust system.

FIG. 7 is a cross-sectional view of the exhaust system taken along aline 7-7 in FIG. 6.

FIG. 8 is a view showing an exhaust muffler in FIG. 6 in an enlargedmanner.

FIG. 9 is a view as viewed in the direction indicated by an arrow 9 inFIG. 8.

FIG. 10 is a view as viewed in the direction indicated by an arrow 10 inFIG. 9.

FIG. 11 is a view as viewed in the direction indicated by an arrow 11 inFIG. 9.

FIG. 12 is a perspective view as viewed in the direction indicated by anarrow 12 in FIG. 6.

DETAILED DESCRIPTION

Certain embodiments are explained in conjunction with attached drawingsFIG. 1 to FIG. 12. In the explanation made hereinafter, the directions“front”, “rear” “left”, “right”, “up” and “down” are determined inaccordance with the directions as viewed from an occupant who rides onan off-road traveling four-wheeled vehicle.

As shown in FIG. 1 to FIG. 3, a pair of left and right front wheels WFis mounted in a suspended manner on a front portion of a vehicle bodyframe F of an off-road traveling four-wheeled vehicle, which is afour-wheeled vehicle, and a pair of left and right rear wheels WR ismounted in a suspended manner on a rear portion of the vehicle bodyframe F.

The vehicle body frame F includes: a pair of left and right lower frames11 extending in the longitudinal direction; a pair of left and rightcenter erected frames 12 erected upward from longitudinally intermediateportions of the lower frames 11; a pair of left and right front sideframes 13 extending frontward from upper ends of the center erectedframes 12, extends frontward and downward from intermediate portionsthereof, and is contiguously connected to front portions of the lowerframes 11; a pair of left and right rear side frames 14 extendingrearward from the upper ends of the center erected frames 12, extendsdownward from intermediate portions thereof, and is contiguouslyconnected to rear portions of the lower frames 11; a center cross member15 which connects upper end portions of the pair of left and rightcenter erected frames 12 to each other; a front cross member 16connecting intermediate bent portions of the pair of left and rightfront side frames 13 to each other; an upper rear cross member 17connecting intermediate bent portions of the pair of left and right rearside frames 14 to each other; and a lower rear cross member 18connecting lower portions of the pair of left and right rear side frames14 to each other.

The pair of left and right center erected frames 12 and the pair of leftand right front side frames 13 are members for defining a profile of afront riding space FS for a driver and a passenger, and a front floor 19arranged in front of the center erected frames 12 is supported on thefront portion of the vehicle body frame F. The pair of left and rightcenter erected frames 12, and the pair of left and right rear sideframes 14, are members for defining a profile of a rear riding space RSfor passengers, and a rear floor 20 arranged behind the center erectedframes 12 is supported on the rear portion of the vehicle body frame F.

In the front riding space FS for the driver and the passenger, adriver's seat 22 arranged behind a steering handle 21 for steering thepair of left and right front wheels WF and a passenger's seat 23arranged on either the left or the right side (such as, for example, aright side in this embodiment) of the driver's seat 22 are arranged in aspaced-apart manner in the vehicle width direction, and the driver'sseat 22, and the passenger's seat 23 are connected to each other with anintermediate connecting portion 24 which functions as a secondpassenger's seat sandwiched therebetween.

The driver's seat 22 and the passenger's seat 23 respectively includeseat portions 22 a, 23 a, and seat back portions 22 b, 23 b, which areerected upward from rear portions of the seat portions 22 a, 23 a. Theintermediate connecting portion 24 includes a seat back portion 24 bdisplaced frontward from the seat back portions 22 b, 23 b, and a seatportion 24 a arranged between the seat portion 22 a of the driver's seat22 and the seat portion 23 a of the passenger's seat 23. The driver'sseat 22, the passenger's seat 23 and the intermediate connecting portion24 are integrally formed as a bench seat 26 elongated in the vehiclewidth direction, and the seat portions 22 a, 23 a, 24 a and the seatback portions 22 b, 23 b, 24 b are integrally and contiguously formed.On the other hand, in the rear riding space RS for passengers, a pair ofleft and right passenger's seats 25 is arranged.

An upper surface of the front floor 19 constitutes a footrest surface 19a for an occupant seated on the bench seat 26. A seat support frame 27which is formed by joining or combining a plurality of pipes andconstitutes a part of the vehicle body frame F has an upper end portion27 a which is arranged along one plane PL, and is formed so as to beerected above the footrest surface 19 a, and the bench seat 26 issupported on the upper end portion 27 a of the seat support frame 27.

A two-cylinder internal combustion engine E which generates power forrotatably driving the pair of left and right front wheels WF, whichconstitute drive wheels and the pair of left and right rear wheels WR,which also constitute drive wheels, is mounted on the vehicle body frameF in a state where the internal combustion engine E is arranged on acenter portion of the vehicle in the longitudinal direction. An enginebody 28 of the internal combustion engine E is mounted on the vehiclebody frame F in a posture where a cylinder axis C (see FIG. 3) isinclined toward a passenger's seat 23 side in the vehicle widthdirection, and the most portion of the engine body 28 is arranged belowthe intermediate portion of the bench seat 26 in the longitudinaldirection, that is, below the intermediate connecting portion 24.

An intake device 29 of the internal combustion engine E includesthrottle bodies 32 connected to intake ports 31 arranged on a leftportion of the cylinder head 3C of the engine body 28 for respectivecylinders, an air cleaner 33 arranged between the driver's seat 22 andthe passenger's seat 23, as viewed in a plan view, a pair of connectingtubes 34, 34 connecting the throttle bodies 32 and the air cleaner 33 toeach other, and a single intake duct 35 introducing air to the aircleaner 33.

The air cleaner 33 is formed in a laterally elongated manner in thevehicle width direction, and is arranged between the seat back portion22 b of the driver's seat 22 and the seat back portion 23 b of thepassenger's seat 23. The seat back portion 24 b of the intermediateconnecting portion 24 arranged between the driver's seat 22 and thepassenger's seat 23 is integrally and contiguously formed with the seatback portion 22 b of the driver's seat 22 and the seat back portion 23 bof the passenger's seat 23, and is displaced frontward from therespective seat back portions 22 b, 23 b. Accordingly, the seat backportion 22 b of the driver's seat 22, the seat back portion 23 b of thepassenger's seat 23, and the seat back portion 24 b of the intermediateconnecting portion 24 form a recessed portion 36 recessed frontward asviewed in a plan view, and the air cleaner 33 is arranged in therecessed portion 36.

A downstream end of the intake duct 35 extending to a right portion ofthe vehicle body along the seat back portion 23 b of the passenger'sseat 23 is connected to a right portion of the air cleaner 33, and a 2Cpre-filter 38 made of dry urethane is detachably filled in an upstreamend of the intake duct 35 so as to remove relatively large foreignsubstances. Resonators 39, 40, 41 are connected to plural portions ofthe intake duct 35.

A fuel injection valve 43 (see FIG. 3) is mounted on the throttle bodies32 of the intake device 29. A fuel tank 44, which stores fuel to besupplied to the respective fuel injection valves 43, and a canister 45,which absorbs a fuel gas evaporated in the fuel tank 44, are supportedon the vehicle body frame F The fuel tank 44 and the canister 45 arearranged below the bench seat 26, which is supported on the upper endportion 27 a of the seat support frame 27 in a separated manner in thevehicle width direction.

At least a part of the engine body 28 and a transmission 46 which iscontiguously mounted on the engine body 28 so as to constitute a powerunit P cooperatively with the internal combustion engine E, are arrangedbelow the intermediate portion of the vehicle in the longitudinaldirection and below the bench seat 26. The fuel tank 44 is arranged onone side (right side) of the transmission 46 in the vehicle widthdirection, and the canister 45 is arranged above the transmission 46.

In FIG. 4, a casing 47 of the canister 45 is formed in a cylindricalshape which is elongated in the vehicle width direction, and has bothends thereof closed. The casing 47 is supported on a pipe 48 extendingin the vehicle width direction so as to form a front end upper portionof the seat support frame 27.

One end portion of an atmospheric air release pipe 49 taking outside airinto the canister 45 is connected to a right end portion of the casing47 of the canister 45. The atmospheric air release pipe 49 extendsfrontward from the canister 45 and, then, extends rearward from thecanister 45 so as to be inverted in a U shape. The other end portion ofthe atmospheric air release pipe 49 is connected to the inside of thepipe 48 of the seat support frame 27. The inside of the pipe 48 isconnected to a front end portion of a pipe 56, which constitutes aportion of the seat support frame 27 and extends in the longitudinaldirection by way of a connecting pipe 57, and a rear end portion of thepipe 56 is released to the atmosphere.

One end portion of a purging conduit pipe 50 for sucking a fuel gas fromthe canister 45 is connected to a left end wall 47 a of the casing 47 ofthe canister 45, and the other end portion of the purging conduit pipeextends rearward below the bench seat 26, and is connected to the intakedevice 29. The intake device 29 is arranged behind the seat back portion24 b, which the intermediate connecting portion 24 of the bench seat 26includes by way of a purging control valve not shown in the drawing.

The fuel tank 44, as shown in FIG. 5, is fixed to a right portion of thevehicle body frame F using a band 42. A fuel pump unit 51 fordischarging fuel in the fuel tank 94 toward the fuel injection valves 43is mounted on a ceiling wall 44 a of the fuel tank 44 in a state where aportion of the fuel pump unit 51 projects above the ceiling wall 44 a.One end portion of a fuel conduit pipe 52 introducing fuel from the fuelpump unit 51 is connected to a fuel discharge pipe 53 mounted on anupper end of the fuel pump unit 51.

A connecting pipe 54 for connecting one end portion of a charge conduitpipe 55 introducing an evaporated fuel in the fuel tank 44 to a canister45 side is arranged in the upper end portion of the fuel pump unit 51such that the connecting pipe 54 projects above the ceiling wall 44 a ofthe fuel tank 44. A bulging portion 44 b bulging above a portion wherethe connecting pipe 59 is arranged, that is, above an upper end portionof the fuel pump unit 51 is formed on the ceiling wall 44 a such thatthe bulging portion 44 b is positioned in front of the connecting pipe54. The bulging portion 44 b and the canister 45 are arranged below thebench seat 26 such that the bulging portion 44 b and the canister 45 arearranged along a front edge 26 a of the bench seat 26.

The other end portion of the charging conduit pipe 55 having one endportion thereof connected to the connecting pipe 54 is connected to aleft end wall 47 a of the casing 47 of the canister 45. ApproximatelyU-shaped bent portions 55 a, 55 b, which are bent so as to bulge outwardin the vehicle width direction, are mounted on both end portions of thecharging conduit pipe 55.

As shown in FIG. 6, a pair of exhaust ports 58 is mounted on one sideportion (such as, for example, a right portion in this embodiment) ofthe cylinder head 30 of the engine body 28 in the vehicle widthdirection. The exhaust ports 58 are connected to an exhaust muffler 59arranged in an extending manner in the vehicle width direction along arear edge of the vehicle body frame F and is supported on the vehiclebody frame F by way of the exhaust pipe passage means 60, whichintroduces an exhaust gas from the exhaust ports 58.

The exhaust pipe passage means 60 includes a pair of individual exhaustpipes 61, 62 with upstream end portions individually connected to theexhaust ports 58, a common exhaust pipe 63 to which the individualexhaust pipes 61, 62 are connected in common, a catalyst converter 64extending in the longitudinal direction between a pair of left and rightsuspensions 73 supporting the pair of left and right rear wheels WR in asuspending manner from the vehicle body frame F, an intermediate exhaustpipe 65 connecting an upstream end of the common exhaust pipe 63 and anupstream end of the catalyst converter 64, and a final exhaust pipe 66which connects a downstream end of the catalyst converter 64 and theexhaust muffler 59.

The pair of individual exhaust pipes 61, 62, the common exhaust pipe 63and a part of the intermediate exhaust pipe 65 form a curved portion 67curved toward the center in the vehicle width direction from one side(right side) of the engine body 28 in the vehicle width direction behindthe engine body 28, as viewed in a plan view, and the exhaust pipepassage means 60 is arranged in an extending manner in the longitudinaldirection while having the bent portion 67.

Further, in the bent portion 67, a joint 68, which separably connectsthe common exhaust pipe 63, which constitutes a portion of the exhaustpipe passage means 60 on an engine body 28 side and a portion of theexhaust pipe passage means 60 on an exhaust muffler 59 side, isinterposed.

As shown in FIG. 7, the joint 68 is configured such that a flange 69,which is fixedly mounted on the common exhaust pipe 63, and a flange 70,which is fixedly mounted on the intermediate exhaust pipe 65, areseparably fastened to each other by, for example, a pair of bolts 71 andwelded nuts 72, which are fixedly mounted on the flange 70. Further, adownstream portion of the common exhaust pipe 63 and an upstream portionof the intermediate exhaust pipe 65 are formed in a frontwardly anddownwardly inclined manner toward a right front side.

The bolts 71 constituting fastening members of the joint 68 are arrangedin an extending manner in the vertical direction while being inclinedfrontwardly and downwardly toward a right front side such that the bolts71 are manipulable from below the vehicle body frame F.

As shown in FIG. 8, a casing 75 of the exhaust muffler 59 is formed intoan approximately cylindrical shape such that both ends of the casing 75are closed by end walls 75 a, 75 b. The inside of the casing 75 ispartitioned into a first chamber 78 defined at a longitudinallyintermediate portion of the casing 75 by a pair of partition walls 76,77, a second chamber 79 defined between a left end wall 75 a of thecasing 75 and the partition wall 76, and a third chamber 80 definedbetween a right end wall 75 b of the casing 75 and the partition wall77.

The final exhaust pipe 66 of the exhaust pipe passage means 60 isconnected to a front side wall of the casing 75 in a communicable mannerwith the first chamber 78, a first communication pipe 81, which makesthe first and second chambers 78, 79 communicated with each other and isfixed to the partition wall 76 in a state where the first communicationpipe 81 penetrates the partition wall 76, and a second communicationpipe 82, which makes the second and the third chambers 79, 80communicated with each other is fixed to the partition walls 76, 77 in astate where the second communication pipe 82 penetrates the partitionwalls 76, 77. A tail pipe 83 that communicates with the third chamber 80is mounted on the right end wall 75 b of the casing 75 with adownstream-end opening portion thereof directed rearwardly anddownwardly.

As shown in FIG. 9 to FIG. 11, the exhaust muffler 59 is covered with aguard member 86 from behind, and the guard member 86 is mounted on thecasing 75 of the exhaust muffler 59 by, for example, three bands 87, 87,87.

Further, the rear floor 20 supported on a rear portion of the vehiclebody frame F is arranged to be positioned above the exhaust muffler 59,and a trailer hitch 88 arranged below the exhaust muffler 59 is fixed tothe rear end of the vehicle body frame F.

Exhaust-muffler-side hooks 89, 90, 91 extending frontwardly are fixedlymounted on a plurality of dispersed portions, for example, threedispersed portions of the exhaust muffler 59. On the other hand, threevehicle-body-frame-side hooks 92, 93, 94, individually corresponding tothe exhaust-muffler-side hooks 89, 90, 91, are fixedly mounted on thevehicle body frame F in a rearwardly extending manner as shown in FIG.6.

As shown in FIG. 12, the exhaust-muffler-side hooks 89 to 91 and thevehicle-body-frame-side hooks 92 to corresponding to each other, areconnected to each other by way of elastic members 95, 96, 97 enablingthe hooks 89 to 91, and 92 to 94 to be inserted into the elastic members95, 96, 97, and to engage with the elastic members 95, 96, 97.

An exhaust-pipe-side hook 98 mounted on the common exhaust pipe 63 ofthe exhaust pipe passage means 60, and a vehicle-body-frame-side hook 99fixedly mounted on the vehicle body frame F, are connected to each otherby way of an elastic member 100, and an exhaust-pipe-side hook 101mounted on the intermediate exhaust pipe 64 of the exhaust pipe passagemeans 60, and a vehicle-body-frame-side hook 102 fixedly mounted on thevehicle body frame F are connected to each other by way of an elasticmember 103.

According to certain embodiments, the driver's seat 22 and thepassenger's seat 23 are integrally formed as the bench seat 26 elongatedin the vehicle width direction together with the intermediate connectingportion 24 connecting the driver's seat 22 and the passenger's seat 23,the upper end portion 27 a of the seat support frame 27, which iserected above the footrest surface 19 a on which the occupant seated onthe bench seat 26 places his feet and constitutes the part of thevehicle body frame F is formed along one plane PL, and the fuel tank 44which stores fuel to be supplied to the internal combustion engine E andthe canister 45 which absorbs a fuel gas evaporated in the fuel tank 44,are arranged in the separated manner in the vehicle width directionbelow the bench seat 26 supported on the upper end portion 27 a of theseat support frame 27. Accordingly, a wide space can be ensured belowthe bench seat 26, and the fuel tank 44 and the canister 45 arrangedparallel to each other in the vehicle width direction are arranged closeto each other in the wide space and hence, a length of a pipe can beshortened.

At least the part of the engine body 28 of the internal combustionengine E and the transmission 46 contiguously mounted on the engine body28 so as to constitute the power unit P cooperatively with the internalcombustion engine E are arranged below the bench seat 26, the fuel tank44 is arranged on one side (a right side in this embodiment) of thetransmission 46 in the vehicle width direction, and the canister 45 isarranged above the transmission 46. Accordingly, a length of a pipebetween the fuel tank 44 and the canister 45 can be shortened, and thecanister 45 can be protected by the transmission 46 from below.

A radiation heat from the transmission 46 is applied to the canister 45arranged above the transmission 46. However, the radiation heat from thetransmission 46 is irradiated in a state where idling of the internalcombustion engine E is sufficiently performed and hence, it is possibleto exclude the influence exerted on a riding comfort by a sudden purgeto the internal combustion engine E attributed to the radiation heat.

The atmospheric air release pipe 49 extending from the canister 45 so asto take in outside air into the canister 45 is connected to the insideof the pipe 48 constituting the part of the seat support frame 27.Accordingly, the seat support frame 27 can be utilized as an intake ductwithout increasing a length of the atmospheric air release pipe 49 and,thus, enhancing a dust intrusion prevention effect.

The cylinder head 30 constituting the part of the engine body 28 and towhich the intake device 29 is connected is arranged behind the seat backportion 24 b which the intermediate connecting portion 24 of the benchseat 26. has, and the purging conduit pipe 50 that introduces the fuelgas sucked from the canister 45 is connected to the intake device 29.Accordingly, the purging conduit pipe 50 can be arranged in the rearwardand upward direction along a lower surface of the seat portion 24 awhich the intermediate connecting portion 24 has with a short pipelength and hence, the stagnation of a gas in the purging conduit pipe 50can be prevented whereby it is possible to suppress the influence of thestagnation of a gas on the performance of the engine.

The connecting pipe 54 for connecting one end portion of the chargingconduit pipe 55 which introduces the evaporated fuel in the fuel tank 44to the canister 45 side is arranged in the fuel tank 44 such that theconnecting pipe 54 projects above the ceiling wall 44 a of the fuel tank44. The bulging portion 44 b bulging above the arrangement portion ofthe connecting pipe 54 is formed on the ceiling wall 44 a such that thebulging portion 44 b is positioned in front of the connecting pipe 54,and the bulging portion 44 b and the canister 45 are arranged below thebench seat 26 such that the bulging portion 44 b and the canister 45 arearranged along the front edge 26 a of the bench seat 26. Accordingly,when a vehicle is on an ascending slope, the canister 45 is positionedabove the connecting pipe 54 and hence, the intrusion of fuel to acanister 45 side can be prevented. When the vehicle is on a descendingslope, fuel is stored in the bulging portion 44 b and hence, theintrusion of fuel into the connecting pipe 54 side can be prevented.

The bent portions 55 a, 55 b having an approximately U shape bent towardthe outside in the vehicle width direction, respectively, are formed onboth end portions of the charging conduit pipe 55. Accordingly, when thevehicle is inclined toward a left side or a right side, the intrusion ofthe fuel to a canister 45 side can be prevented by these bent portions55 a, 55 b and, thus, enhancing the fuel intrusion preventionperformance against the inclination of the vehicle.

Exhaust ports 58 are formed on one side portion (such as, for example,right side portion in this embodiment) of the engine body 28 along thevehicle width direction, the exhaust ports 58 are connected to theexhaust muffler 59 arranged in an extending manner in the vehicle widthdirection along a rear edge of the vehicle body frame F by way of theexhaust pipe passage means 60 introducing an exhaust gas from theexhaust ports 58, and the exhaust pipe passage means 60 is arranged inan extending manner in the longitudinal direction while having the bentportion 67 bent toward the center in the vehicle width direction fromone side (such as, for example, right side in this embodiment) of theengine body 28 in the vehicle width direction behind the engine body 28as viewed in a plan view. Accordingly, it is possible to ensure theengine performance by ensuring a pipe passage length from the exhaustports 58 to the exhaust muffler 59 while decreasing bending of theexhaust pipe passage means 60. Further, the exhaust muffler 59 isarranged in an extending manner in the vehicle width direction along therear edge of the vehicle body frame F and hence, an excellent noiseprevention effect can be obtained by ensuring a volume of the exhaustmuffler 59.

The exhaust pipe passage means 60 includes the catalyst converter 64extending in the longitudinal direction between the pair of left andright suspensions 73 supporting the pair of left and right rear wheelsWR on the vehicle body frame F in a suspending manner. Accordingly,compared to the structure where a catalyst is stored in the inside ofthe exhaust muffler 59, it is possible to acquire an excellent noiseprevention effect by sufficiently ensuring a volume of the exhaustmuffler 59. Further, a heat generating portion attributed to a catalystcan be positioned away from the outside by covering the heat generatingportion with the left and right suspensions 73 and the rear exhaustmuffler 59.

At the bent portion 67 of the exhaust pipe passage means 60, the joint68 that separably connects a portion of the exhaust pipe passage means60 on the engine body 28 side and a portion of the exhaust pipe passagemeans 60 on the exhaust muffler 59 side is interposed,. Bolts 71 of thejoint 68 are arranged in an extending manner in the vertical directionwhile being inclined frontwardly and downwardly toward a right frontside in a state where the bolts 71 can be manipulated from below thevehicle body frame F. Accordingly, a pipe passage length of the exhaustpipe passage means 60 can be ensured and, at the same time, fasteningand separating operations of the joint 68 can be performed from belowthe vehicle body frame F thus enhancing maintainability.

Exhaust-muffler-side hooks 89, 90, 91 extending toward a front side arefixedly mounted on a plurality of dispersed portions of the exhaustmuffler 59, and a plurality of vehicle-body-frame-side hooks 92, 93, 94individually corresponding to the exhaust-muffler-side hooks 89, 90, 91,extend toward a rear side and are fixed to the vehicle body frame F. Theexhaust-muffler-side hooks 89, 90, 91 and the vehicle-body-frame-sidehooks 92, 93, 94 corresponding to each other, are connected to eachother by way of the elastic members 95, 96, 97 which enable the hooks 89to 91, and 92 to 94 to be inserted into the elastic members 95, 96, 97and to engage with the elastic members 95, 96, 97. Accordingly, theexhaust muffler 59 can be easily assembled to the vehicle body frame Ffrom behind the vehicle body frame F and hence, assembling property canbe enhanced.

The rear floor 20 positioned above the exhaust muffler 59 covered withthe guard member 86 from behind is supported on the rear portion of thevehicle body frame F, and the trailer hitch 88 arranged below theexhaust muffler 59 is fixed to a rear end of the vehicle body frame F.Accordingly, it is possible to miniaturize the guard member 86 dedicatedto covering the exhaust muffler 59 by protecting the exhaust muffler 59with the rear floor 20 and the trailer hitch 88 from above and below.

Although certain embodiments of the present invention has been explainedheretofore, the invention is not limited to the above-mentionedembodiment, and various design modifications may be made withoutdeparting from the invention described in claims.

For example, certain embodiments of the present invention are notlimited to an off-road traveling four-wheeled vehicle, and are broadlyapplicable to other vehicles.

DESCRIPTION OF REFERENCE NUMERALS AND SIGNS

-   20: rear floor-   28: engine body-   46: transmission-   58: exhaust port-   59: exhaust muffler-   60: exhaust pipe passage means-   67: bent portion-   68: joint-   71: bolt constituting fastening member-   73: suspension-   86: guard member-   88: trailer hitch-   89, 90, 91: exhaust-muffler-side hook-   92, 93, 94: vehicle-body-frame-side hook-   95, 96, 97: elastic member-   E: internal combustion engine-   F: vehicle body frame-   P: power unit

We claim:
 1. A vehicle, comprising: an internal combustion engine havingan engine body; and a transmission contiguously mounted on the enginebody so as to constitute a power unit cooperatively with the internalcombustion engine, wherein the transmission and engine body are mountedon an intermediate portion of a vehicle body frame in the longitudinaldirection of the vehicle, wherein an exhaust port is formed on one sideportion of the engine body along the vehicle width direction, whereinthe exhaust port is connected to an exhaust muffler disposed in anextending manner in the vehicle width direction along a rear edge of thevehicle body frame by way of an exhaust pipe passage that introduces anexhaust gas from the exhaust port, and wherein the exhaust pipe passageis disposed in an extending manner in the longitudinal direction of thevehicle while having a bent portion bent toward the center in thevehicle width direction from one side of the engine body in the vehiclewidth direction behind the engine body as viewed in a plan view.
 2. Thevehicle according to claim 1, wherein the exhaust pipe passage includesa catalyst, converter extending in the longitudinal direction of thevehicle between a pair of left and right suspensions supporting a pairof left and right rear wheels on the vehicle body frame in a suspendingmanner.
 3. The vehicle according to claim 1, wherein a joint separablyconnects a portion of the exhaust pipe passage on an engine body sideand a portion of the exhaust pipe passage on an exhaust muffler side toeach other, and is interposed in the bent portion of the exhaust pipepassage, and wherein a fastening member of the joint is disposed in anextending manner in the vertical direction in a frontwardly anddownwardly inclined manner to enable the manipulation of the fasteningmember from below the vehicle body frame.
 4. The vehicle according toclaim 1, wherein exhaust-muffler-side hooks extending toward a frontside are fixedly mounted on a plurality of dispersed portions of theexhaust muffler, wherein a plurality of vehicle-body-frame-side hooksindividually corresponding to the exhaust-muffler-side hooks are fixedlymounted on the vehicle body frame in an extending manner toward a rearside, and wherein the exhaust-muffler-side hooks and thevehicle-body-frame-side hooks corresponding to each other are connectedto each other by way of elastic members configured to enable the hooksto be inserted into the elastic members and to engage with the elasticmembers.
 5. The vehicle according to claim 1, wherein a rear floorpositioned above the exhaust muffler covered with a guard member frombehind is supported on a rear portion of the vehicle body frame, andwherein a trailer hitch disposed below the exhaust muffler is fixed to arear end of the vehicle body frame.
 6. A vehicle, comprising: aninternal combustion engine means for providing motor power, saidinternal combustion engine means including engine body means; and atransmission means for transmitting the motor power of the internalcombustion engine, said transmission means contiguously mounted on theengine body means so as to constitute a power unit cooperatively withthe internal combustion engine, wherein the transmission means andengine body means are mounted on an intermediate portion of a vehiclebody frame means in the longitudinal direction of the vehicle, whereinan exhaust port means is formed on one side portion of the engine bodymeans along the vehicle width direction, wherein the exhaust port meansis connected to an exhaust muffler means disposed in an extending mannerin the vehicle width direction along a rear edge of the vehicle bodyframe means by way of an exhaust pipe passage means that introduces anexhaust gas from the exhaust port means, and wherein the exhaust pipepassage means is disposed in an extending manner in the longitudinaldirection of the vehicle while having a bent portion bent toward thecenter in the vehicle width direction from one side of the engine bodymeans in the vehicle width direction behind the engine body means asviewed in a plan view.
 7. The vehicle according to claim 6, wherein theexhaust pipe passage means includes a catalyst converter means extendingin the longitudinal direction of the vehicle between a pair of left andright suspension means supporting a pair of left and right rear wheelmeans on the vehicle body frame means in a suspending manner.
 8. Thevehicle according to claim 6, wherein a joint means separably connects aportion of the exhaust pipe passage means on an engine body side and aportion of the exhaust pipe passage means on an exhaust muffler side toeach other, and is interposed in the bent portion of the exhaust pipepassage means, and wherein a fastening member means of the joint meansis disposed in an extending manner in the vertical direction in afrontwardly and downwardly inclined manner to enable the manipulation ofthe fastening member means from below the vehicle body frame means. 9.The vehicle according to claim 6, wherein exhaust-muffler-side hookmeans extending toward a front side are fixedly mounted on a pluralityof dispersed portions of the exhaust muffler means, wherein a pluralityof vehicle-body-frame-side hook means individually corresponding to theexhaust-muffler-side hook means are fixedly mounted on the vehicle bodyframe means in an extending manner toward a rear side, and wherein theexhaust-muffler-side hook means and the vehicle-body-frame-side hookmeans corresponding to each other are connected to each other by way ofelastic member means for enabling the hooks to be inserted into theelastic member means and to engage with the elastic members.
 10. Thevehicle according to claim 6, wherein a rear floor positioned above theexhaust muffler covered with a guard member from behind is supported ona rear portion of the vehicle body frame, and wherein a trailer hitchdisposed below the exhaust muffler is fixed to a rear end of the vehiclebody frame.
 11. An exhaust system mounting structure for a vehicle,wherein said exhaust system mounting structure comprises: an exhaustport formed on one side portion of an engine body along a vehicle widthdirection, wherein the exhaust port is connected to an exhaust mufflerarranged in an extending manner in the vehicle width direction along arear edge of a vehicle body frame by way of an exhaust pipe passage thatintroduces an exhaust gas from the exhaust port, and wherein the exhaustpipe passage is arranged in an extending manner in the longitudinaldirection of the vehicle while having a bent portion toward the centerin the vehicle width direction from one side of the engine body in thevehicle width direction behind the engine body as viewed in a plan view.12. The exhaust system mounting structure according to claim 11, whereinthe exhaust pipe passage includes a catalyst converter extending in thelongitudinal direction of the vehicle between a pair of left and rightsuspensions supporting a pair of left and right rear wheels on thevehicle body frame in a suspending manner.
 13. The exhaust systemmounting structure according to claim 11, wherein a joint separablyconnects a portion of the exhaust pipe passage on an engine body sideand a portion of the exhaust pipe passage on an exhaust muffler side toeach other, and is interposed in the bent portion of the exhaust pipepassage, and wherein a fastening member of the joint is disposed in anextending manner in the vertical direction in a frontwardly anddownwardly inclined manner to enable the manipulation of the fasteningmember from below the vehicle body frame.
 14. The exhaust systemmounting structure according to claim 11, wherein exhaust-muffler-sidehooks extending toward a front side are fixedly mounted on a pluralityof dispersed portions of the exhaust muffler, wherein a plurality ofvehicle-body-frame-side hooks individually corresponding to theexhaust-muffler-side hooks are fixedly mounted on the vehicle body framein an extending manner toward a rear side, and wherein theexhaust-muffler-side hooks and the vehicle-body-frame-side hookscorresponding to each other are connected to each other by way ofelastic members configured to enable the hooks to be inserted into theelastic members and to engage with the elastic members.
 15. The exhaustsystem mounting structure according to claim 11, wherein a rear floorpositioned above the exhaust muffler covered with a guard member frombehind is supported on a rear portion of the vehicle body frame, andwherein a trailer hitch disposed below the exhaust muffler is fixed to arear end of the vehicle body frame.